Draft control



I. E. STEELE DRAFT CONTROL Sept. 8, 1931.

Filed Dec. 9, 1929 Patented Sept. 8, 1931 PATENT. OFFICE IRA E. STEELE, F SIOUX CITY, 1OWA DRAFT CONTROL Application filed December 9, 1929.

My invention relates to draft controls of the type wherein an opening is provided in the chimney of a furnace, boiler or the like, and this opening closed by a swinging .5 closure, responsive to the pull of the draft within the chimney so that it will disclose the opening to a greater or less extent n proportion to the amount of suction wlthin the chimney.

An object of the present invention is to provide a draft control which is basically automatic in operatiomincluding means for exerting -a counter-pull against the suctlon of the chimney but which is also provided with manually controlled means for changing said counter-pull so as to increase or decrease the strength of the counter-pull.

A further object is to provide an arrangement in-which the actionof the draft control device is at all times automatic, the manual control being utilized only for the purpose of changing the strength. of the counter-pull.

Another object is to provide an arrangement in which the manual control can be so adjusted that the change in the counterpull will take effect automatically at a certain position of the closure, allowing the closure to swing during a portion of its path of movement against the action ofone counter-pull and subjecting it to a different counter-pull when it passes a given point in its swing.

A further object of my invention is to provide a structure which is simple, durable and inexpensive in construction for carrying out the above functions.

A further object of my invention is to provide astructure embodying a manual control device of the above character which may easily be arranged to act in unison wit a plurality of closures.

A further object of my invention is to provide a particular form of manual control device which is particularly adapted to cooperate with an automatic swinging draft control of the type that is now in use com- ;rising a closure hinged at its lower edge in a chimney opening and a counter-weight secured to the closure and extending below Serial No. 412,681.

the hinge and outside of the chimney so as to resist inward swinging of the closure.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawings, in which:

Fig. 1 is a side elevation of a draft control embodyin the present invention.

Fig. 2 is a vertical, sectional view through the same taken on the line 2-2 of Fig. 1.

Fig. 3 is an edge elevation of the same, a furnace door control power arrangement for operating the manual-control device being shown in connection therewith.

Fig. 4 is a side elevation of a double closure unit embodying the present invention.

I have used the reference character to indicate generally a chimney or draft flue of the type employed in connection with an ordinary furnace or boiler. In installing my invention, an opening 11 (Fig. 2) is provided in the chimney below the connection of the smoke pipe of the furnace or boiler with the chimney. A casing 12 of cast iron or the like is adapted to be secured to the chimney within the opening 11 and is provided with a facing flange 13, which rests against the outer surface of the chimney 10. At the lower extremity of the easing 12, the flange 13 extends upwardly as at 14 and a pair of openings 15 are provided in the portion 14 to receive the fingers 16 of the closure member '17.

The casing 12 is formed with a peripheral shoulder 18 which extends downwardly and outwardly in a diagonal direction and the closure 17 seats against the shoulder 18.

It will now be seen that the closure 17 is hinged by means of the fingers 16 for swinging movement about its lower edge and is limited in its outward swinging to a posi' tion engaged against the shoulder v18.

Inward movement of the closure 17 is opposed by a primary control device comprising a counter-weight 19, threaded upon the threaded end of a rod 21, which is secured to the closure 17 and extended clownwardly beyond the hinge axis thereof.

The suction of the draft within the chimney will tend to pull the closure 17 inwardly, the opening thus disclosed gradually increasing as the closure moves inwardly. The extent of inward movement of the closure 17 will thus depend upon the suction within the chimney.

The effect upon a fire of the automatic draft control is well-known. Should the fire have a tendency to burn too rapidly, the increased suction produced by the increased draft through the furnace will cause the closure 17 to swing inwardly, thus releasing the suction in the chimney so as to reduce the draft upon the fire. The result will be a uniformity of combustion which can be obtained in no other manner.

I have discovered that an automatic draft control will reduce the consumption of coal as high as in many instances. It prevents smoking of the chimney.

I have discovered that the usefulness of the automatic draft control can be very materially increased by providing means for manually varying its operation. It is undesirable that said manual control be such as to rob the device of its automatic action. Consequently, as stated in the objects of the invention, it is the purpose of my present invention to provide a manual control which is effective to vary the action of the auto- .matic control while allowing it to remain automatic.

This has been achieved by providing anoted or hinged to the casing 12 or to the chimney in such a manner that it is extended across the path of upward movement of the rod 21 or the weight 19. The particular mounting shown comprises a yoke 22, the side arms of which are pivoted at 23 to arms 24, formed on the casing 12 and the cross bar of which is provided with an out wardly projecting rod 25, threaded at 26 and received in an internally threaded counterweight 27.

A chain 28 is secured to the auxiliary counter-weight B and is extended upwardly to a manual control operating device 99, which may be of any conventional form.

By raising or lowering the chain 28, the auxiliary counter-weight B may be adjusted to any of a series of positions, from an treme lowered position, where it constantly engages the primary control device A, to an extreme upper position, wherein it will not affect the primary control device A dur ing any portion of the swing of the closure. Between these two extreme positions there will be a plurality of intermediate positions wherein the action of the manual control device will commence after the closure has opened a predetermined amount.

It will be readily seen that the action oi the manual control device will be to increase the resistance of the primary control device, in other words, to increase the counter-pull of the closure against the sucticn of the chimney.

The amount of increase can be adjusted by adjustment of the counter-weight 27 on the shaft B. The amount of the primary resistance of the counter-weight A can likewise be adjusted.

I have found that it is highly desirable under certain conditions to increase the counter-pull after the closure has opened a certain amount. By setting the manual control so that the auxiliary counter-weight takes effect after the closure has partly opened, the adjustment of the balance between the closure 17 and the primary control device may be made more delicate so that the closure will respond to lesser variations in the suction within the chimney when the draft is small.

The initial control while the fire is getting under way may thus be made more delicate without sacrificing the efiiciency of the control of the fire after the draft has increased. Under other conditions, it may be desirable to throw the full load of both counter-weights on the closure from the very beginning so as to strengthen the draft as much as possible at the beginning on a day when it is diificult to start a fire.

Under other conditions, it may be desirable to remove the eflect of the auxiliary control entirely from the primary control. For instance, after a fire has been started, with both controls in full operation so as to encourage the draft as much as possible, it may be desirable to suddenly check the draft and by pulling the auxiliary counterweight to its extreme upper position, the draft control will be given free rein to function in its automatic manner.

Since the primary usefulness of the manual control resides in varying the effect of the automatic control during and after starting a fire or during the interval when coal is being shoveled into the furnace or boiler, the present invention may be embodied in a furnace door control type of apparatus as shown in Fig. 3. Instead of the manual control device 29, a drum 30 is provided mounted on the shaft of an electric motor 31, which is controlled by a twoway switch 32 positioned to be engaged by a suitable projection 33 on the door 34 of the furnace when the latter is opened. As the door 34 swings from closed to open position, it will momentarily close one side of the switch and as the door swings from open to closed position, it will momentarily close the other side of the switch. The

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switch is of the type having a switch lever adapted to assume a neutral position under spring pressure and the projection 33 is of such length that it will first engage the lever 35 and then swing past the lever 35 so as to engage it from the other side when the door is being moved in a reverse direction.

Assuming the door 34 to be open and being moved toward closed position, the switch 32 will be operated to close a circuit 36, including a solenoid or other magnetic control 37, adapted to release a latch hook 38. The latch hook 38 is pivoted at 39 to the casing 12 and is adapted to engage a finger 40 on the yoke 22 to support the auxiliary control device in raised position.

As the door 34: is moved from closed to open position, the other side of the switch 32 will be closed to energize a circuit 41 including the electric motor 31, whereby the chain 28 will be wound upon the drum 30 and the auxiliary control device raised until it latches with the hook 38. The clutch is provided to allow a slippage between the motor and the drum 30 should the motor operate longer than the time required for raising the auxiliary control device.

It will now be seen that the door control device is so arranged that when the door of a furnace is opened for shoveling in coal the auxiliary counter-weight will be dropped into position to move the automatic draft control toward closed position- When the furnace door is closed, the auxiliary counter-weight will be raised to allow the automatic draft control to again function fully as a check draft.

The invention is particularly applicable to a plurality of closures embodied in a single unit, as shown in Fig. 4. I find that a plurality of closures of moderate size will operate much better than one single closure of large size. In applying the present invention to a plurality of closures, the yoke 22 is made wide enough so as to extend across all of the rods 20.

Some changes may be made in the construction and arrangement of, the parts of my invention without departing from the real spirit and purpose of my invention.

I claim as my invention:

1. In a draft control, in combination with a flue having a draft check opening therein, a closure hinged at its lower extremity to the flue and adapted to move inwardly, a counterweight secured to the closure and projecting below the hinge axis thereof, and adapted to urge the closure toward a position wherein it will close the opening, a variable control comprising an auxiliary weight hinged to the flue and adapted to obstruct the path of upward movement of the counterweight, and an auxiliary control device for raising the auxiliary weight to any of a series of positions wherein it may allow partial or full swing of the counterweight without interfering therewith.

2. In a draft control, a casing adapted to be secured toa flue to outline a draft check opening therein, a closure hinged at its lower extremity to the casing, and adapted to move into the flue, a counterweight secured to the closure and projecting below the hinge thereof and adapted to urge the closure toward closed position, an auxiliary weight hinged to the casing and normally obstructing the path of upward movement of the counterweight, and an auxiliary control device for raising the auxiliary weight to any of a series of positions wherein it may allow partial or full swing of the counterweight without interfering therewith.

3. In a draft control, in combination with a flue having a draft check opening therein, a closure hinged at its lower extremity to the flue and adapted to move inwardly, a counterweight secured to the closure and projecting below the hinge axis thereof, and adapted to urge the closure toward a position wherein it will close the opening, a variable control device having a portion adapted to obstruct the path of upward movement of the counterweight, said variable control device including means to exert a downward pull against said portion and an auxiliary control device for variably limiting the downward movement of said portion.

4. In a draft control, in combination with a flue having a draft check opening therein. a closure hinged at its lower extremity to the flue and adapted to move inwardly, a primary control device adapted to-constantly exert an outward pull against the closure to resist suction produced by a draft within the flue, said primary control device including a projecting member secured to the closure and swingingly movable therewith, a variable control device having a portion adapted to obstruct the path of movement of said projecting member, said variable control device including means to exert a pull against said portion in a direction to be cumulative of the pull of the primary control device, and an auxiliary control device for variably limiting the movement of said portion in the direction of its pull.

5. In a draft control, in combination with a flue having a draft check opening therein, a closure hinged at its lower extremity to the flue and adapted to move inwardly, a counterweight secured to the closure and projecting below the hinge axis thereof, and adapted to urge the closure toward a position wherein it will close the opening, a variable control device having a portion adapted to obstruct the path of upward movement of the counterweight, said variable control device including means to exert a downward pull against said portion and an automatic control device for variably limiting the downward movement of said variable control device, including an electric switch, means secured to furnace door to ope ate said switch when the door is opened and an electric motor-powered hoisting device operatively connected with the variable control and controlled by said switch.

6. In a draft control, in combination with a flue having a draft check opening therein, a closure hinged at its lower extremity to the flue and adapted to move inwardly, a primary control device adapted to constantly exert an outward pull against the closure to resist suction produced by a draft within the flue, said primary control device includ ing a projecting member secured to the closure and swingingly movable therewith, in an upward direction when the closure moves inwardly, a variable control comprising an auxiliary weight hinged to the flue and adapted to obstruct the path of movement of said projecting member when the closure is moving inwardly, and an auxiliary control device for variably limiting the movement of said portion in the direction of its pull.

7. In a draft control, a casing adapted to i be secured to a flue to outline a draft check opening therein, a closure hinged at its lowor extremity to the casing, and adapted to move into the flue, a counterweight secured to the closure and projecting below the hinge thereof and adapted to urge the closure toward closed position, an auxiliary weight hinged to the casing and normally obstructing the path of upward movement of the counterweight, and a manual control device for raising the auxiliary weight to any of a series of positions wherein it may allow parial or full swing of the counterweight with out interfering therewith.

Signed this 15th day of November, 1929,

l in the county of VVoodbury and State of lowa.

IRA E. STEELE. 

